1. The EEG tracings taken during metrazol treatment of 9 psychotic patients are reported.2. Four of the 9 cases showed no temporary or permanent change in the quality of the EEG tracings other than those changes appearing during and immediately following each metrazol injection. These 4 cases received 6 or less injections each, with one exception, case 4, which received 11 injections.3. Changes of a temporary nature lasting days or weeks appeared in 3 of the 9 cases, the three cases receiving 9 to 14 injections.4. The 2 cases who received the greatest number of shocks, 18 and 20 injections respectively, showed permanent abnormal changes in the character of the brain potentials.5. It is concluded that temporary changes in the brain potentials lasting days or weeks may occur in cases receiving in the neighborhood of 10 injections and changes of a permanent character may be expected in those cases receiving 20 or more injections.Abstract Teaser